Chairs are known which have frames in the form of a curved backplate to which a backrest cushion is secured. The backrest cushion stretches from the seat cushion to the top edge of the backplate. When the backplate is moved back and forth, the backrest cushion moves with it, being displaced to a greater extent in the upper region than in the lower because of the chosen position of the pivot at the base. The movement achieves only a slight change in the depth of the seat in the lower region, and the user is obliged to incline the body according to the position of the backrest. Consequently, the optimal body inclination is not possible in all backrest positions. For example, when the backrest is pivoted to its most forward position, it is not possible to adopt a relaxed upright posture because the edge of the backrest extends too far forward at the top.